Known techniques of compressively coding text messages include fixed dictionary techniques and adaptive dictionary techniques, in which a table of tokens is maintained at both a transmitter and a receiver. The table of tokens, or token table, associates a word of data symbols with a character or sequence of characters in an alphanumeric, or text, message. In both the fixed and adaptive dictionary techniques, frequently used sequences of characters, including all the necessary single characters of the alphabet, numbers, and punctuation characters, are included in the token table or tables. During compression encoding, sequences of characters in the text messages are sought which match a sequence within the token table and the matching sequence of characters is replaced by the token, with the expectation of shortening the number of data symbols needed to communicate the text message. The process is repeated in reverse at the receiver.
Fixed dictionary techniques have been used for many years, while adaptive dictionary techniques have proliferated extensively in the last several years during the continued burgeoning of data communications. Although fixed dictionary techniques have been successfully used for long data files, they are not as efficient as adaptive dictionary techniques for the transfer of long data files, which explains the investigation and success of adaptive compression techniques in recent years
Some communication systems, such as paging systems, provide message communication of messages which are quite short on the average, in comparison to many other systems. For these systems, the overhead involved in an adaptive compression coding technique is typically not as efficient as using a fixed dictionary technique. However, existing fixed dictionary techniques themselves have not evolved significantly in the last decade and have been oriented towards longer messages.
Thus, what is needed is an improved fixed dictionary technique for compressively encoding and decoding short text messages. Such a technique would, of course provide compression of a long message as well